The present invention relates to IC (integrated circuit) card technology, and technology effectively applied to, e.g., semiconductor memory card (hereinafter referred to as a memory card).
Memory cards such as multimedia cards (standardized by the multimedia organization), SD memory cards (standardized by the SD card organization) or memory sticks (registered trademark of Sony Corp.) are a kind of storage devices to store information in their internal semiconductor memory chips. Since access can be made directly and electrically to nonvolatile memories of semiconductor memory chips without mechanical control, the memory cards have the excellent advantages of faster write and read speeds and easier replacement of storage media in comparison with other storage devices. Since the memory cards are compact in size and light in weight, they are primarily used as auxiliary storage devices of portable electronic devices such as portable personal computers, cellular phones, or digital cameras.
The appearance of a multimedia card is formed by a square-planar thin-plate cap having a corner largely chamfered. A memory body is fitted in and bonded to a recess on a parts mounting surface of the cap. The memory body includes a wiring board and semiconductor chips mounted on its principal surface. The semiconductor chips are sealed by a sealing part and are electrically connected with plural external terminals on the back surface of the wiring board through wiring of the wiring board. The plural external terminals on the back surface of the wiring board are exposed to the outside to be electrically connected with an electronic device in which the multimedia card is to be incorporated. The appearance of the above-mentioned SD card is formed by bonding together two square-planar thin-plate cases each having a corner largely chamfered. A memory body is sandwiched between the two cases. Plural openings are formed on the bask surface of one case of the SD card, and plural external terminals of the memory body are exposed from the openings. Through the openings of the case, the external terminals of the SD card and an electronic device in which the SD card is to be incorporated are electrically connected. The appearance of the above-mentioned memory stick is a rectangular thin plate having a corner largely chamfered. Like the SD card, a memory body is sandwiched between two cases.
By the way, in conventional multimedia cards, sufficient measures have not been taken against action of forcibly extracting the multimedia cards inserted into electronic devices and against cases where the multimedia cards pop out when the electronic devices drop. However, since the multimedia cards have often been used in electronic devices such as cellular phones and mobile computers, more and more electronic devices have had a slot structure so that the multimedia cards can be easily removed, for convenience of users' use. As a result, there has been an increase in action of forcibly extracting the multimedia cards and cases where the multimedia cards pop out readily when the electronic devices drop, and therefore it has become important to take appropriate measures against such situations.
In the above-mentioned SD card, sides of the two cases are provided with recesses penetrating from the principal surface to the back surface of the two cases, and the recesses are engaged with retainers of an electronic device. This construction prevents an SD card from being forcibly removed or from popping out readily due to slight impact (see Patent Documents 1, 2, and 3).
In the above-mentioned memory stick, a recess for fixing the memory stick in a desired position is provided at an edge of a case side at which external terminals of the case are exposed (see Patent Document 4).    [Patent document 1] Japanese Unexamined Patent Publication No. 2003-6576    [Patent document 2] Japanese Unexamined Patent Publication No. 2003-86293    [Patent document 3] Japanese Unexamined Patent Publication No. 2003-86296    [Patent document 4] Japanese Unexamined Patent Publication No. 2003-91700